With the rapid development of the Internet and digitization technologies, there are more and more digital contents for online transaction, such as electronic books, electronic newspapers, music, movies, pictures, games and software. However, since digital contents are subject to copy and propagation, digital contents for online transaction are confronted with a large quantity of piracies and infringements, which jeopardize the interests of digital content owners and dampens their enthusiasm for expanding business via the Internet. Thus, it gets increasingly important to protect the copyright of digital contents.
The DRM technology has received more importance in recent years, and there is an ever growing increase in DRM protected digital contents. As a result, the value-added service of digital contents can be accomplished. For example, while publishing paper books, publishing houses can gain more earnings from online sales of electronic books via a DRM system.
FIG. 1 depicts a general architecture of a DRM system 100. System 100 comprises a content distributor 110, a rights issuer 120, a consumer 130 and a mastering center 140. Mastering center 140 holds the protected digital contents and the rights of the contents. Content distributor 110 acquires intended distributing digital content and provides a distribution mechanism of the content. Rights issuer 120 is responsible for managing registering consumer 130, authenticating consumer 130, receiving a license (rights object) request related to the digital content from consumer 130, generating a license for the digital content, sending the license to consumer 130 and recording the consumption of the license of consumer 130. Consumer 130 acquires downloadable or streaming content from content distributor 110 and requests rights issuer 120 for a license of the corresponding content so as to use the protected content. Consumer 130 must have digital content presentation tools (such as computer, mobile phone, personal digital assistant (PDA) and the like, having a player, reader and the like.) that support DRM, which tools decrypt digital content from content distributor 110 by using the license from rights issuer 120, so as to represent the digital content. During the process of content distribution and authentication, content distributor 110 and rights issuer 120 need to communicate with mastering center 140. More specifically, mastering center 140 provides content distributor 110 with protected digital content and provides rights issuer 120 with usage rules of the digital content.
In the traditional DRM system, the DRM agent device, namely the user device, such as computer, mobile phone and set-top box, and the user account are treated as the same entity, and the account is valid only for one rights issuer. It is unreasonable for many business modes, for example, IPTV. On one hand, the user might use more than one DRM agent device by the same account, and one DRM agent device may be used by more than one user with their accounts. On the other hand, in the DRM system, one account should be supported by more than one rights issuer.